For Joomla 1.0.12

Using this component you can have registered users and upcoming new registered users synchronized from one Joomla site to all other listed Joomla sites - no matter where the sites are located!
Warning! This component is not compatible with Joomla 1.0.13 yet.

F.ex. you have installed the component at the Main Site, where the user makes a new account or there are some existing registered users. In the component you list which other sites to have the user being registered on. After you have synchronized the users manually once, you dont need to do this again. New users are handled by auto - also if they change user info.

BUT:

It could also be the other way around: You have a subsite with registered users or new users are registered and you want them to be registered on the Main Site.

So there are really many ways to handle this by choosing which sites to address.

The synchronization is done ON ALL THE SERVERS YOU HAVE ACCESS TO!!

In Joomla (the Main Site) you install the component called SynchronizeUsers via Installers – Components

You go to Components – SynchronizeUsers – Set source site:
Here you see a page where you must enter the info for the source site. The default values for Main Site is shown but can be changed to another site.

You go to Components – SynchronizeUsers – List Subsites:
Here you see a page ready to list the added subsites to have synchronized – now it is empty.

Click the button Add

Write a Name, the URL to the subsite database, the database name + db-user + password

Click the button Add

And so on – list as many subsites you want!

When all the wanted subsites are listed go to Components – SynchronizeUsers – Synchronize.
Here you see a page with all the subsites listed. There is a check box at the beginning of each listed subsite – if you check this, the subsite is included in the operation to come.

When the wanted subsites are checked you press one of the buttons:

* Synchronize Main to Subsites - and the users from the Main Site are merged/written in the selected subsites database. In this way existing users in the Main site database are handled (this is only needed if the component is installed after having users being registered. If it is a new Joomla install without any users this sync is not needed!)
* Synchronize Subsites to Main - and all the users on the listed subsites are written to the Main database

If a user or an e-mail already exists the user is not written to the database but is shown on a error list after the operation.

Now all the users from the Main Site are in the database for the selected subsites .

SO: from now the synchronizing is done automatically FOR THE LISTED SUBSITES when a user register on the Main site.

Go to Components – SynchronizeUsers – About License
Here you can see some info about the license disclaimer. The license is for ONE install on ONE domain. There is a discount for more licenses.

WHAT ABOUT COMMUNITY BUILDER AND OTHER COMPONENTS LIKE THAT??

Q:Problems with CommunityBuilder and other components when trying to replace com_register and com_user
A:In this SynchonizeUsers version users’ synchronization cannot be done while registration or while profile modification in the presence of such components.

What can be done?
Synchronization through admin panel for CommunityBuilder can be done.
With all this it is necessary to indicate CommunityBuilder table names on subsites and mainsite.
But anyway synchronization while registration and profile modification will be impossible.